Why do all-over printed underwear colours fade?

Short answer: Print fading usually comes from one of four causes: dye that was not fully fixed or washed off after printing, pigment binder wearing away so pigment particles leave the fabric, washing and drying conditions harsher than the print can take, or rubbing in high-wear areas. Reactive-printed cotton depends on correct steaming and washing-off; if unfixed dye remains, the first washes remove it and the colour drops. Pigment prints sit on the surface in a binder, so they wear faster where fabric rubs, such as the seat and inner thigh. Bleach, optical brighteners in detergents, high temperatures and tumble drying all speed fading. Test colour fastness to washing with ISO 105-C06 and assess change with the ISO 105-A02 grey scale, set care instructions that match the results, and confirm the printing process with the mill.

Common causes

• Incomplete fixation or wash-off after reactive printing.
• Pigment binder not fully cured or too little binder.
• Hot washing, chlorine bleach or harsh detergents.
• Abrasion in high-wear zones.
• Light exposure when drying outdoors.

How to diagnose

• Compare faded and new pieces against the approved standard on a grey scale.
• Check whether fading is even (washing) or local (rubbing).
• Ask the mill which process, ink type and fixation settings were used for the lot.
• Wash retained samples from the same lot under the care label conditions.

Testing

• Colour fastness to washing with ISO 105-C06, choosing the test condition closest to the care label.
• Assess change in colour with the ISO 105-A02 grey scale.
• Repeat washing with an ISO 6330 procedure for several cycles to see cumulative fading.

Care labels

In the US, the Care Labeling Rule requires care labels to give a regular care method that will not harm the product, and to warn against parts of the usual procedure that would. If the print fades with hot water, the label should say so, for example by giving a lower temperature.

A worked example

If ten washes at 40 °C cause clear fading, but a lab test at that condition shows acceptable change, the problem may be detergent, tumble drying or how customers actually wash. Ask a few customers how they wash, then repeat the test with a common household detergent and drying. If the test also fails, the print process or ink choice needs to change before the next order.

Dark and bright colours

Deep navy, black, red and bright fashion shades usually need the most dye or pigment, so they are most likely to show loss. Ask the mill whether the darkest colourways need an extra wash-off or a fixing step, and test them first.

Limits

Real washing conditions vary widely. Lab tests predict performance but do not cover every household.

Facts, recommendations and uncertainty

Established: fading comes from incomplete fixation, binder wear, harsh laundering and rubbing. Recommendation: test washing fastness and grey-scale change, and match care labels to results. Uncertain: how consumers actually wash, which can exceed test conditions.

Sources and further reading

• ISO 105-C06:2010 — Colour fastness to domestic and commercial laundering
• ISO 105-A02:1993 — Grey scale for assessing change in colour
• ISO 6330:2021 — Domestic washing and drying procedures for textile testing
• U.S. FTC — Care Labeling Rule (16 CFR Part 423)

Standards and regulations are referenced by their published scope. Test parameters, cycles and pass levels should be agreed with your laboratory for the specific product; legal requirements should be confirmed for each destination market.